


Good Cop, Bad Doggy

by smoothpeachbutt



Series: Everyday With You - Dimileth NSFW One-Shots [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe, Alternate Universe - Modern Setting, BDSM, Chains, Costumes, Creampie, Dimileth Week 2020 (Fire Emblem), Doggy Style, Dom/sub, Explicit Sexual Content, F/M, Fluff and Smut, Halloween Costumes, Light BDSM, Light Dom/sub, Modern AU, Oral Sex, Restraints, Roleplay, Rough Body Play, Rough Oral Sex, Rough Sex, Semi-Public Sex, Sexual Roleplay, Vaginal Sex
Language: English
Status: Completed
Published: 2020-11-14
Updated: 2020-11-14
Packaged: 2021-03-09 19:55:19
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,115
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27551893
Author URL: https://archiveofourown.org/users/smoothpeachbutt/pseuds/smoothpeachbutt
Summary: It's Halloween, and when Dimitri falls short of expectations, Byleth decides to punish him in a whole different way.
Relationships: Dimitri Alexandre Blaiddyd & My Unit | Byleth, Dimitri Alexandre Blaiddyd/My Unit | Byleth
Series: Everyday With You - Dimileth NSFW One-Shots [1]
Series URL: https://archiveofourown.org/series/2013946
Comments: 4
Kudos: 54





	Good Cop, Bad Doggy

**Author's Note:**

> Suuuuuper late for F!Dimileth NSFW Week. Was planning to do a couple of fics for each prompt (and I still will!!!) but I hope this fic satisfies the first 3 days of prompts, namely:  
> Day 1- Creampie and/or Restraints  
> Day 2 – Reunion  
> Day 3 - Costumes
> 
> This will be part of a collection of one-shots of the "filler days" in an AU Dimi- and Claude-leth longfic that I've yet to release! :)

“Ms. Byleth! Caspar took my candy!!!”

Byleth whirled around and was greeted by a bashful Bernadetta, clinging unto her pants on the verge of tears. She had just finished attending to another preschooler, and now a problem between the class bully and the crybaby had just popped up. _Great. Where the hell was Dimitri?_

“Caspar, give Bernadetta her candy basket back,” Byleth bellowed towards the end of the room, where the six year-old in question was jumping around with two pumpkin baskets. The party music around the room was loud, but Byleth made sure to make her teacher voice much louder, partly threatening. “Give it over, or flashcards for you on Monday.”

Caspar froze in his tracks with the warning, then sulked over to his teacher. He held out the basket towards the fairy-costumed Bernadetta, who grabbed it quickly and ran away.

“See? She doesn’t even want to share!” cried out the young boy. “Why doesn’t the fairy want to share with Peter Pan?? I knew I should’ve gone as a policeman like you!” Caspar continued his light tantrum and stomped off to presumably torment the other kids. 

Byleth sighed weakly while patting down her attire. She didn’t _hate_ Halloween, but she never really got the concept of dressing up. But as the designated teacher chaperone for the orphanage’s annual Halloween Party, she had to cough up something _viable_ , or the kids would cry. She at least tried to pick a costume with authority…although the kids weren’t buying the bad cop demeanor. If she could have had her way, Byleth would’ve put on pajamas and go as a TV binge-watcher, or what teenagers were calling “Netteflix & Chill”. She didn’t even have Netteflix. But Dimitri has one at his place, and they would definitely “chill”… 

_Where the fuck is Dimitri??_

“Byleth, I’m here. I apologize for my tardiness.” 

_Speak of the devil. Who was sweaty. And not wearing the right costume._

Byleth bit her lip, annoyed. She forced a smile for the embarrassed Dimitri, not really able to get mad at her boss, her boyfriend, her supposed ‘policeman partner’ in this annoying kid’s party, and now, her… dog??

“What are you wearing, Dimitri?” Byleth grit her teeth as she gave his costume a look down. He was clad in some light brown velour or faux fur jumpsuit fashioned like a puppy, complete with paws, a hood with ears, and a tail. To others it may have seemed adorable, but to Byleth, it represented her frustration. This was _not_ their agreed partner costume. 

The blonde knew she was frustrated, her fists already turning white. He placed his hands-slash-paws on her shoulders, trying to calm her down. 

“I know what you’re about to say. I’m really sorry I couldn’t open the party with you, but Dedue and I had to find a new costume. And this was the only one…”

Byleth blinked in confusion. “What do you mean? I gave Dedue the policeman costume so you could change right away.”

“Yes, and right as I arrived at the airport, I changed into it as promised,” Dimitri answered, then quickly looked sideways with a light flush on his face. “But uhm…it ripped.”

Byleth’s jaw dropped open. She could hear a faint call from one of the preschoolers, but she chose to ignore it and focus on his confession. “It _ripped?_ It was too tight??” she questioned with a raised voice, but not enough to really be heard by others. “B-but that was…”

“I’m sorry Beloved. I know you borrowed this from your Uncle’s unit. I will pay him back and buy the whole force new uniforms.”

He’s right— these were true blue police uniforms that she had begged for from her uncle, Alois Rangeld, the head of the local police department. But it was hard to deny Dimitri when she tried playing the scenario in her head: him innocently forcing his huge biceps and wide chest into the jacket, with the sound of fabric ripping and buttons falling apart likely turning him white in anguish. How could she get mad at a man who was offering to buy a whole taskforce’s supply of uniforms, something he could well afford but didn’t really need to invest on? And judging by his huffing and puffing and genuine look of concern, he seemed to have really scrambled for an alternative costume, when his handsome features, tall, muscular figure, and charming, honest smile could have passed off as a costume anyway? 

‘A God Amongst Men’? 

To top it all off, this sorry excuse for a costume wasn’t...so sorry after all. Where onesies like this were usually loose and lazy, his was tight-fitting, seams threatening to burst and the zipper by his neck straining to stay up. But most importantly, the fit gave emphasis to his southern region, and Byleth started to chuckle at the sight of a round and long bulge. Likely not hard, but with his well-endowment, it was difficult to tell sometimes. 

Yep, she couldn’t stay angry at this man.

“You don’t have to do that, Dimitri” she said, referring to her uncle’s squad. She nudged downward towards his package and gave a sly smile. “But you should do something about _that._ ”

Dimitri blushed as he looked down at his little Dimitri, which was surprisingly starting to become big Dimitri, hardening at Byleth’s mere mention. Maybe it was her beautiful doe eyes or her tantalizingly smug grin. Or perhaps it was her policewoman costume, perfectly accentuating her curves and oh-so-snug in all the right places, like her tight button down hiding her _own_ well-endowed package. 

Byleth noticed his searching eyes and growing erection and lightly slapped his arm. “Are you being serious right now??”

“If you looked at mine, I could look at yours too, right?”

The green-haired woman scoffed and turned to a nearby table to grab a piece of cloth. “Goddess, just put this apron on and go play with the kids,” she said, handing over the cloth but with her back to him. “At least they can play with a cute little doggy.”

Dimitri took the apron and tied it around his waist, successfully covering his questionable bulge. He then slowly approached her from behind until he towered over her small figure. Dimitri took a deep breath, and when no preschooler was present, reached around Byleth’s arms to grope her ample chest. He leaned into her ear and whispered with a smirk. “Yes, master. I will obey.”

Ah, so he was playing this game too. Something good must have happened at his overseas conference to contribute to this much boldness. Although she found this exchange amusing, she had to put up a front. She was supposed to be the bad cop in the equation tonight. 

She pushed him away and slapped his arm playfully, this time with fake irritation. “You’re getting punished for that later, Mr. Blaiddyd. Just you wait.”

Dimitri only winked back.  
\-----------------------------------

The ride home was short yet exhilarating. 

Dimitri couldn’t keep his hands off Byleth all night at the party, secretly palming her ass when he could stand behind her. And that continued in Dimitri’s limo, the blonde requesting Dedue to drive so he could continue his handiwork in the backseat. Once the partition was rolled up, Dimitri wasted no time to place her on his lap, feeling her breasts, her tiny waist, and her firm, round behind all through her costume. He took care not to remove her clothes lest he rip it again, especially if they were to still alight the car to reach his apartment. But his desire ran hot as he worked her with his tongue, hungrily kissing Byleth from her mouth down to her tits, sucking her nipples through the blue-colored fabric. 

Byleth was moaning left and right, unable to hold her passion for much longer as Dimitri started to grind his still-erect shaft against her core. Despite the optical privacy, she was sure Dedue could hear them from up front. Although he probably knew all about their shenanigans anyway, Byleth was still embarrassed to face Dimitri’s calm bodyguard considering the wet stains the former was giving her. 

_Damn him and his hot mouth._ She was really going to make Dimitri pay for this tonight.

The minute they passed through the doorway of his apartment, Dimitri lunged forward like an animal to grab his lover. But his patience was to be tested, as Byleth stopped him with a finger to his lips, confusing the man. She stepped into his space gingerly, then used her left hand to cup his cheek, tiptoeing upwards to meet his lips. It was a slow kiss, a stark contrast from their car ride. Both melted into the kiss with eyes closed, causing Dimitri to give in to the tenderness and calm down from his hunger. 

_Click._

Dimitri’s eyes flew open at the feel of cold metal around both wrists, which he realized in two seconds were bound together behind his back. He turned to look over his shoulder but suddenly felt a clasp tighten around his neck.

Another _click._

“Byleth… what’s this…?” he asked, breathless from the kiss and the confusion. He soon realized he was backed up against the living room wall, and that his sneakily swift girlfriend had cuffed his hands during a moment of passion. He tried walking towards her, but was pulled back forcefully around his neck… with a metal chain.

“I had it installed today. They did a pretty good job after all.”

“Did you… plan this? For Halloween?” Dimitri asked, half nervous and half… _excited_. “B-but I’m supposed to be your police partner. Why have me locked up?”

“As the corrupt policeman-turned-prisoner, what else?” she replied, eyes twinkling with her imagined fantasy. “And yes, Dimitri, this was always going to end up with you in chains. Though your attire now works too… because remember—who’s a bad doggy?” 

Byleth grasped his member through the velour, gaining a deep groan from the blonde. “You did this to me earlier, right doggy? Now you’ll have to be punished.” She tugged on it more forcefully, which sent Dimitri plummeting back down into his dark void of desire. He keened to her touch, wanting so very bad to grind in her palm. But she pulled her hand away and shook a finger in his face. 

“No, doggy. You don’t do that until I tell you to. You only listen to what I say, got it?” Dimitri nodded meekly and Byleth grinned in satisfaction. “Good. Now doggy— _sit_ ”, she said with some dominance. 

Dimitri wasn’t naturally one to interrupt, but her commanding tone left him completely speechless and pliant, falling into her gaze. He started to kneel as instructed, feeling the chain attached to his neck uncoil, reaching almost maximum tautness when he was finally on his knees. Dimitri realized that she had planned this perfectly, ensuring he would be staying put in chains tonight. He gulped at the thought—an experience he, at least, had never gone through. He wondered briefly if Byleth had ever been chained up before…

“Good. Now stay there and watch me.”

Byleth stepped back and pulled her ponytail, tousling her wavy green hair first before letting it flow naturally onto her shoulders. She licked her lips and started at her buttons, slowly revealing her clavicle and chest, each groan of Dimitri encouraging her to unveil more of her smooth flesh. She stopped unbuttoning where the black lace lining of her bra peeked through, but as she moved closer to him, her hardening nipples popped out as well, deciding to be released from their uncomfortably tight confines. Similarly, Dimitri’s core was getting uncomfortable too.

“Byleth… I want…”

Byleth cut him off by stepping on his member, eliciting a deep, guttural groan from Dimitri. She worried for a second if she had pressed too forcefully, then observed Dimitri purse his lips together, likely holding in another moan of pleasure. “You’re supposed to call me _Master_ ,” she said, resuming her role. When Dimitri didn’t respond right away, Byleth pressed down further with her foot, and pulled his jaw upwards with a forceful hand.

“Tsk tsk, such a bad doggy. You need to be taught a lesson,” she seethed. Hovering high over his kneeling figure, Byleth positioned her crotch right in his face. “Take off my pants with your mouth.”

 _Ah, this was her agenda._ “Yes, Master.”

Dimitri looked up at her demanding yet gorgeous visage—a face that he could never deny. He proceeded with his orders, first pressing his lips against the fabric to find the top button. His hot breath sent a small shiver through Byleth, and he heard her grumble to keep her composure. Keeping his eyes on her face, he started undoing the button with his lips, then proceeded to capture her pant zipper between his teeth, pulling it down painfully slow as if to taunt her back. Catching his tactic, Byleth glared right down and grabbed the back of his blonde locks.

“Bad dog! Hurry up and undress me!” she hissed, forcing his face against her in annoyance. Dimitri complied and used a few motions to tug at the sides of her pants, allowing them to slide off her hips and finally reveal her most sacred cave of wonders, covered in a sheer, black lace thong. Dimitri salivated at the sight of a growing wet spot at the bottom of the fabric. His master was leaking, and they had only kissed tonight.

Byleth bit her lips as she followed Dimitri’s line of sight. “Look what you’ve done to me. You’re making me drop on the floor,” she said, panting. True enough, a thin trail of slick had seeped from the sides of her thong, trickling down her inner thighs. She gripped his hair once again and commanded her pet. 

“Now, clean me up.”

Without a second thought, Dimitri happily obeyed and dove straight for her core, licking a stripe right along the center. 

_Shit._ Byleth was the epitome of _wet_ , even more than he expected. He could taste her sweet nectar right through the fabric, and it drove him positively ravenous. Dimitri licked along her center further, causing the outline of her labia to form. He then sucked on her folds, eliciting a moan from his master. Byleth rubbed her pussy against his mouth to seek more friction, and Dimitri’s tongue took the cue to expertly squirm under the fabric and make contact with her soft, wet skin. 

Byleth grabbed his head with both hands at the first touch alone, the heat of his hungry muscle sending a shockwave of electricity throughout her whole body. He knew she was touch-starved, just as much as he and his aching member were. He was in an uncomfortable position—knees aching from the hard marble floor, wrists chaffing against the metal cuffs, neck straining from the tight clasp of his collar, where the chain was at maximum length and limiting his movements. And not to mention his extremely hard dick, screaming painfully in its inflexible confines. He wanted so badly to touch her, hold her hips and take control as he usually did. But this new, bound experience— _damn, he fucking loved it_. The restraints only added to his hot, burning desire to have Byleth, the only flavor he could taste with his impaired tongue. 

Dimitri rose to the challenge of his incapacity by increasing his pace and going as deep as possible. He buried his face firmly against her mound so he could reach further inside her folds. He licked and sucked on every possible crevice, drinking up all her sweet, addicting juices. He found her clit, partly unhooded but already swollen. As soon as the tip of his tongue met the tiny bulb, Byleth shook wildly, her Achilles’ Heel finally exposed.

Dimitri thought she would finally yield, but the always unpredictable Byleth would not give up so easily. She settled each leg on either side of his face, thereby straddling his strong, broad shoulders. She tugged on the chain attached to his collar and thrust her core deeper into his mouth. 

“Nghhh doggy, don’t stop! Eat me, eat me!” she demanded, totally out of character whether from tonight’s bad cop persona, or as Byleth, his cool and refined girlfriend. Dimitri continued his attacks on her clit, sucking on the nub vigorously. He would alternate between the swollen bulb and her extremely wet hole, darting his tongue in as deep as possible. Without any hands to hold her hips, Byleth held on for dear life by crushing his face between her legs, almost suffocating Dimitri. 

“Yes doggy, mmmnnnn… such a good doggy! Goddess, yes right there!!” With her angry moans and her hand forcefully yanking his hair, he knew it was time to drive her over the edge. With a few more tiny bites on her clit, Byleth’s orgasm crashed in a heavy wave, the woman screaming her lover’s name in ecstasy. She came in full force, her juices dripping all over Dimitri’s mouth, chin and neck. 

When she finally came down from her high, Byleth attempted to slither off Dimitri’s shoulders, but trembling legs caused her to stumble to the floor. Dimitri called her name in concern, but upon seeing Byleth on her hands and knees, wet ass and folds in the air as if in presentation to him, his worry quickly turned into an aching need. His adrenaline shot through, and with his hunger renewed, he used his inhuman strength to break free from the cuffs, still a godly feat even with the fake, costume-grade metal. With his hands now free, he tore off the clasp around his neck, then ripped open his fur costume, the impossibly hot and tight last layer of restraint he had on. 

Byleth was left aghast at the sight of Dimitri behind her, his lone blue eye seemingly red with either anger or burning passion. She knew he was strong, but _metal-breaking strong_? Goddess, fuck no. And to think those cheap-ass cuffs set her back 30 bucks. She gulped as his humungous, vein-protruding cock sprang free from his torn jumpsuit, looking like a steel rod or police baton ready to punish. Byleth opened her mouth to say a word, but a hard slap across her butt then made her realize that tonight’s dynamics had finally reversed. 

_She_ was now the bad doggy.

Dimtiri’s large hands spread her legs open, and another loud spank landed on her ass cheeks. “You thought you could chain me up, huh?” he growled. He lowered himself so his mouth breathed hot against her ear, which effectively pressed his thick cock against the curve of her swollen ass. “Who’s the master now?”

He timed a bite on her ear with a hard thrust into her sex. Byleth screamed at the forceful entry, immediately filling her up to the brim. That thrust alone made her weak, and her arms gave way as her face landed sideways on the floor. The new master returned upright, steadying his deep plunges with rough hands at her hips, likely bruising. Despite her earlier orgasm, Byleth felt her extreme tightness, and it took a full minute for the pain to convert into pure pleasure, allowing her to see stars.

Dimitri himself was heady as he rammed his throbbing cock into her hole. Her insides were so perfect for his seven-inch member, and her wetness coated their connected skin each time he plunged deep into her womb. Her ass was red from his spanking, but the way they bounced with each of his thrusts only encouraged him to continue his rough assault. 

“This is your doing, you bad dog. If you hadn’t bound me earlier, _you_ wouldn’t be getting this punishment,” he huffed, reaching to grab one of Byleth’s wrists and folding it secure behind her back. “Look, I don’t even need those inefficient cuffs to restrain you.” 

“Please, Dima—”

Another loud spank. 

“Insolent bitch. Call me Master!” 

Byleth’s eyes widened at his tone and choice of words. This wasn’t their first rough play, but the way he fucked her wildly and assumed a much bolder, dominant personality was new to her…to them both. But she could hardly process anything for longer than a few seconds, considering how her pleasure spot was being abused over and over. He slapped her again and Byleth yelped, finally obeying his command. 

“Master…. My master…”

Dimitri smirked, knowing that her usually defiant nature was being suppressed by her impending orgasm. She could not communicate her wishes, but he knew what to give her needy cunt to drive both of them to completion. 

He stood from the floor, bringing Byleth’s hips up with him and staying unsheathed in her folds. Byleth’s body naturally followed upright, but Dimitri instead pushed her back down, effectively folding her body by the hip. 

“Stay down, dog” he growled with a smug grin. “Because I’ll fuck you like one.”

And so he did. The wildest and strongest he’s ever done.

Byleth’s moans were interspersed with “fuck”, “yes”, and a lot of pleading “Master”. If Dimitri hadn’t pulled her arms from behind, holding her like a wheelbarrow, she’d fall over with each hard and fast thrust. She wasn’t going to last long in this animalistic position, considering Dimitri’s inhuman pounding. And she knew he wouldn’t either. 

Dimitri’s breath was ragged as he felt her pussy start to clench. As she held unto him, he did so too with his vice grip on her hips, pulling them forcefully up and down his cock. 

“Tell me—who’s the master you serve?” he managed to command one last time.

“You, Dima! You’re my master!”

“Take it, Byleth!!!” Dimitri yanked her upwards with a last thrust, and the sudden shift in position sent both of them shouting with their climax. Dimitri released a huge load into her, and her own creamy white fluids gushed from her hole, their mixed cum dripping along their thighs and to the floor. Dimitri brought Byleth’s face around to meet her quivering lips, finally kissing her passionately as he continued to pulse into her core. 

They gasped for air when Dimitri finally pulled out of Byleth, spilling some excess fluids from her pussy onto the floor. But neither of them cared about the mess considering their intense tryst. Dimitri picked the weak Byleth up in his arms and carried her to the nearby sofa. He cradled her in his lap, rubbing her sides gently while leaving light kisses around her neck. 

“Beloved, are you okay?” he whispered, returning to his normal, gentle self. “Maybe I went too far…”

Byleth cupped his face and brought it up to hers, gazing into his lone ocean-blue eye. “No, Dima. I’m fine. But that… wow, I don’t know what to say.”

He kissed her again. “Well, it was definitely… different. We’ve never done that before… oh, sorry. _I_ haven’t. I’m not sure if you…”

“I haven’t either,” Byleth said sheepishly, looking down with a shy smile. “I saw it online and I thought it’d be something we could do on our first Halloween together. Though, I don’t know if you really liked it... especially with the um… collar...”

Dimitri laughed a full, hearty one then pressed her tighter against his chest. “It was perfect, _baby_ ,” he uttered her secret pet name, one that Byleth loved but was too embarrassed for it to be heard publicly. “We can do it anytime you want. Tomorrow, even. After breakfast?”

“If I’ll even get up tomorrow. I don’t think I’ll be able to walk…”

“Then it’s good that tomorrow’s the weekend. I’ll carry you around the whole apartment.” 

Byleth chuckled at the suggestion, then suddenly remembered the broken materials on the floor. "Dimitri! You broke the cuffs and collar!" she exclaimed, partly in surprise of his strength as she slapped his arm playfully. "How the hell did you even do that?"

"Sorry, but you have to admit—those were a pretty flimsy pair of cuffs." Dimitri smiled, kissing her on the forehead. "Next time, get the same pair so I can break free and take you again." 

The woman scoffed, punching him lightly in the gut with her boyfriend's smug comment. They shared a laugh, and after Byleth pressed her lips tenderly against his, caressing his face and golden hair, collecting warmth from their insatiable passion. Dimitri did the same, staring into her mesmerizing, large green orbs that kept him sane, alive, and peaceful. “I’ve missed this. I’ve missed you.” He whispered under his breath, in awe of his beautiful woman and happy to finally be back in her arms.

Byleth smiled and nuzzled into the groove of his neck, finding solace with her lover. “Welcome home, Dima.”

**Author's Note:**

> waaaah my first time writing female dom!! but I couldn't resist switching back to canon because who doesn't love feral Dima? :D  
> I created a twitter!! Follow me @smoothpeachbutt for... a lot of Dimileth and Claudeleth he he
> 
> Comments and feedback always appreciated!!!


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